Tappet



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' A. ADDYMAN ET AL.

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A. DDYMN ET Al..

TAPPET Filed April 1, 1927 2 sheets-sheet 2 @M M m w df W M A0/v4 M M Pb/ENTER@ Mww N .w w

Patented June 12, 1928.

ARTHUR ADDYMAN AN-D EDWARD` BELLAVANCE, OF PLYMOUTH, MASSACHUSETTS.

TAPPET.

Application filed April 1,

The invention relates to an improvement in tappets for internal combustion engines. 'lhe tappet is used in those connections where a valve normally held in a closed po. sition is intermittently opened by means of suitable cams upon a cam shaft and allowed to close in timed relation to the other op-Y erating parts of the engine. During the operation of the valve inorder to provide for itsproper opening and closure a certain clearance niust` be left in the parts forming the link of connection between the cam shaft and the valve and this clearance will vary for different types of engine, as for example betweeen extremes of ..004 and .012 of an inch. This clearance should be provided for with exactness and should not be left 'to guesswork as is commonly the case. Besides, the adjustment for clearance is often left to an inexperienced or careless workman. Accordingly it is one of t-he essential objects of the invention in the present tappet, which forms one of the links between the cam shaft and the valve, to provide that a proper clearance shall be obtained with exactness in a very simple manner and checked by a mere glance of the eye or touch of the finger.

The closure of the valve is effected by a relatively powerful sprin and in the operation of the valve it is esirable that it `be eased onto its valve seat in closing instead i of closing with a sharp impact which results in a noisy valve which is objectionable. In the same connection when clearance is provided' for in the operation of the valve it is desirable that provision shall also be made for rendering the connections as noiseless as possible. A further object of the invention is to meet both these requirements in the present tappet.

The tappet can best be seen and understood by reference to the drawings in which those parts only of an engine are shown as are necessary for a proper understanding of the invention, and in which- Figure, 1 is a view partly in vertical section and partly in side elevation ot the tappet with associated parts.

Fig. 2 is the same as Fig. 1 showing a slightly changed position of certain parts of the tappet and parts associated with it.

Fig. 3 is a vertical section of the tappet.

Fig. 4 is a vertical section of a portion of the tappet showing a slight modilication of 1927. Serial No. 180,128.

the structure to which reference will later be made, and

Fig. 5 is a View partly in vertical section and partly in side elevation of the tappet applled to a valvular construction in which Va rocker arm forms one of the intermediate connections between the cani shaft and the rvalve.

Referring to the drawings 1 represents the tappet body, which is of a type commonly employed. 'It is arranged to reciprocate within a iixture '2 forming a part of the engine casing (not shown) and whlch fixture acts as a guide for the tappet body. The tappet body is reciprocated from 0H av cam shaft (not shown) byvmeans of a cam notshown), the reciprocation beingeffecte in the usual manner. i

3 is a valve which is controlled by connect1ons of which the tappet body forms a part. This valve controls a port 4 in a valve casing of which 5 represents a part or fragment thereof. The valve closesragainst a Valve seat 6 on the casing at the entrance to the port therein. i7frepresents the Stem of the valve. This stem extends through a fixture 8 forming a part of the engine casing and acts asa guide for the stem. The valve is maintalned in a normal closed position by means -of a compression spring 9 interposed between the lixture 8 and a collar 10 on the stem of the valve.

The tappet body l located beneath the stem 7 of the valve is boredand internally threaded. Fitting therein with adjustment thereon is an adjusting screw having a threaded shank 12 and head 13. 'The adjusting screw is held in a determinate adjusted position with relation to the tappet body by means of a lock nut 14 arranged on the threaded shank of the screw and tightening against said body.

The head 13 of the tappet screw has within it a socket 15. This socket extends from. the top surface of thehead and terminates in a bottom 16 located above the bottom surwith the shank of the tappet screw, but it is preferred that there be arranged 1 1 on the shank of the contact tappet beneath t 1e head one or more washers 2() of fibrous material which may be considered in the resent connection and will be later referre to as forming a part of the head of the contact ta et. The head of the contact tappet fits sli a ly within the socket in the head of the tappet screw and the shank of the contact tappet extends into the bore 17 of the tappet screw. Arranged, also, within the bore 17 of the tappet screw beneath the end of the shank of the contact tappet and withv bearing against this end and with bearing also against the tappet screw at the bottom of the bore within it, is a compression spring 21.

This spring permits of the head of the contact tappet having contact with the bottom 16 of the socket 15 of the tappet screw within which the 'head is contained but with a normal tendency to dis lace the head of the contact tappet out of t 1e socket 15 substantially as shown in Fig. 3.

The depth or' thickness of the head 18 of the contact tappet bears a certain relation to the depth of the socket 15 within which it is contained. In other words, when the head is bearingv against the bottom 16 of the socket a determinate s ace 22 will' separate the top surface 23 o the head of the contacty tappet from the top surface 24 of the head of the tappet screw.- The 'space 22 thus provided is the's ace which ermits, as will laterbe explaine of such c e'arance being left in the connections through which the valve 3 is operated as will insure a proper operating working of the valve and of which connections the tappet forms a part aspreviously described. The amount of space left between the to surface of the contact tappet and that of t e tappet screw will depend upon the particular object or engine in oonnection with which the tappet is used and may vary in amount, as for example from .004 to .012 of an inch or otherwise as may be desired, all being provided by variance in the depth of the head of the contact tappet. Where fibrous washers 20 are used in forming the head of the contact tappet the proper amount of space may very easily be provided, by variance in the thickness of the washers. v

In the setting ofthe parts, with the valve 3 in its normal closed position, the tappet screw is adjustably moved and set by the lock nut 14 when the top surface 23 of the head of the contact tappet, then engaging the lower end of the'valve stem7, will lie just flush with the top surface 24 o the tappet screw (see Fig. 1). This may be determined by a lance of the eye or a touch of the finger. T e head of the contact tapet will then occupy a position elevated wit 1n the socket 15 of the tappet screw engaging the lower end of the valve stem by action of the compression spring 2l beneath its shank, and will leave a clearance space 22 to engage the bottom surface 25 of the head of the contact tappet when the tappet screw through the contact tappet and stem of the valve will operate to open the valve 3, both the springs 9 and 21 then being further compressed. Upon the movement of the tappet ody in a reverse direction for permitting closure of the valve 3 by the spring 9, the valve will first close no faster than is permitted by the reverse movement of the tappet body as long as the bottom surface 25 of the head of the contact tappet is in contact with the bottom surface 16 of the socket in the tappet screw, the spring 21 then continuing under compression. When the re verse movement of the tappet body has con-` tinued so far that the surface 16 of 'the tappet screw draws away from the bottom surface 25 of the contact tappet, the spring 21 then tending to close it. The spring 9, however, bein the stron er spring, will close the valve, ut the resu ting action is to ease the valve onto its valve seat.

In Fig. 4 there is shown a slight modification n that instead of building up the head of the contact tappet with one or more fibrous washers a washer 20 is left to form a part of the head and a separate fibrous washer or packing is disposed in the bottom of the socket 15 to form a fibrous lining for this socket at this point. With the fibrous washers thus disposed the relative arrangement of the parts will be precisely the same as before described, one fibrous washer being` considered a part of the head of the tappet screw and the other a part of the head of the contact tappet, the respective washers then presenting opposing surfaces 16 and 25 respectively, forming as they do one the bottom of the socket 15 of the adjustin screw and the other the bottom surface of t 1e contact tappet. The advantage of locatn the washers in this way is that libre will ave contact with libre in the operation of the tappet instead of fibre havin contact with metal as in the construction rst described, the contact of libre with fibre being preferred. iIt will also be noted that in either case the depth of the head of the socket in` the tappet screw will bear a determinate relation to the depth of the head of the contact tappet for initially providing the clearance space, all as previously described.

In Fig. 5 there is shown a further adaptation of the invention in that the improved tappet is shown applied to a valvular construction in which a rocker arm forms one of the intermediate connections between the cam shaft and the valve for controlling the valve. In this construction 30 is the valve controllin the port 31 in the valve casing 32, the va ve closing against the valve seat lthe shank of the contact tap 33 on said casing. 34 representsthe stem of the valve. The valve is held in a normal closed position by means of a spring 35 interposed between a stem collar 36 and .the casing 32. Arranged to have bearing-against the top end of the valvel stem 1s a rocker arm 37 having a. pivotal mounting 38 on the casing. Extendingthrough the outer end of the rocker arm and threaded to turn therein is an adjusting screw 39. The adjusting screw is held 1n a determinate ad- ]usted position with relation to the rocker arm by means of a lock nut 40 arranged upon the screw and tightening agalnst the rocker arm. The adjusting screw 39 is provided on its lower end with a ball 41. This ball is socketed within the head 42 of a contact tappet, 43 representing its shank. The contact ta pet fits within a tappet member having a ead 44 and a shank 45.` The head 44 of the tappet member has within it a socket 46, 47 representing the bottom of this socket. The tappet member is also provided with a bore 48 which extends through the lower end of its head and into its shank. The head 42 Aor' the contact tappet fits within the socket 46v of the tappet member, the shank 43 of the contact tappet extending downwardly into the bore 48 of the tappet member. Located within the bore 48 beneath the end of et with bearing against this end and wit bearing also against the tappet member at the bottom of the bore is a compression spring 49. For obtaining a contact of libre against ibre between the head of the contact tappet and the bottom of the socket within which it is contained ibrous washers 20 are preferably provided as in the construction first described. Attached to the lower end of the tappet member is a lift-in rod 50 operated byla cam (not shown) w ich cam 1n turn is operated by a cam shaft (not shown) in the usual manner. The head of the contact tappet is socketed to bear the same determinate relation to the head of the tappet member within which it is contained as did the head. of the contact tappet in the construction first described. In other words, the arrangement is such thatwhen the head 42 of the contact tappet is engaging the bottom surface 47 of the socket within which it is contained a determinate space will separate the top surface 51 of the head of the contact tappet from the top surface 52 of y the head of the tappet member so that when these two top surfaces are brought flush with one another the same determinate space,

represented as the space 53, will in the setting of the parts constitute a clearance space between the head of the contact tappet and the bottom of the socket in the tappet member within which it is contained, all precisely as in the construction first described.

In the setting of the parts, with the valve 30 in its normal closed position the screw 39 is ad'ustably moved and setby the lock nut 40 w en the top surface 51 of the head of the contact tappet, then against the ball 41 on the adjusting screw by the spring 48, will lie flush with Athe top surface 52 of the tappet member. This may be determined by a. glance of the eye or a touch of the finger. This leaves a determinate clearance 53 in the line of connection between the cam shaftv and the valve. At the same time all of the connected parts will be held in yielding Contact with one another by reason of the action of the spring 48, the end of the rocker arm being held against the end ofthe valve stem. n

As the tappet member is lifted in the operation of the parts for rocking the arm 37 and opening the valve the head of the tappet member will be brought into engagement with the head of the contact tappet for effeet-ing this operation after `first-passing through the clearance space. Upon the reyieldingly held verse movement of the parts for permitting the closure of the valve .the valve will first close no faster than is' permitted by the reverse movement of the tappet member as long as the tappet member is in contact with the head of the contact tappet, the spring 48 then continuing under compression. When the reverse move-ment of the tappet member has continued so far that it begins to draw away from the head of the contact tappet the valve will be closed by the action of the spring 35, but it will be eased onto vits .valve seat by the counter-action of the spring 48 reacting a ainst the spring 35, all substantially as in t e construction first described.

Having thus fully described our invention, we claim and desire Ato secure by Letters Patent of the United States 1. In a valve mechanism for internal combustion engines, a tappet member having a socket in its head and a bore extendingfrom the bottom of the socket into the body of the member, a valve displacing contact tappet having a head and shank, the head of said contact tappet fitting within the socket of said tappxet member with normal bearing against t e bottom of said socket and the shank of the contact tappet extending into the bore of the tappet member, a com ression spring arranged within the bore o the tappet, member below the shank of the conof the tappet member.

2. A tappet for internal combustion engines comprising a tap et body, a tappet.

screw adjustable in the ody, a nut on the tappet screw for holding it in adjusted position relatively to the tappet body, the tappet screw having a socket in its head and a bore extending from the bottom of the socket into the body of the screw, a valve displacing contact tappet having a head and shank, the head of said contact tappet tting within said socket of the tappet screw with normal bearing against the bottom of said socket and the shank of the contact tappet extending into the bore of the tappet screw, and a compression spring arranged within the bore of the tappet screw below the shank of the d contact tappet acting normally to unseat the contact ta pet and elevate the head thereof above the bottom of the socket within which it is contained, the head of said contact ta pet bearing such relationto the socket witgin which it is contained that when the head of the contact tappet is in position contacting with the bottom of said socket with said spring under compression a determinate space will separate the top surface of the head of the contact tappet from the top surface of the head of the tappet screw, the head of said contact tappet bearin also such relation to the socket within w lich it is contained that in the setting of the parts the tappet member and the contact tappet may be adjustably set in such determinate relative position thaty the top surface of the head of the contact tappet will be flush with the top surface of the head of the tappet mein4 ber.

ARTHUR ADDYMAN. EDWARD BELLAVANCE. 

